Stepper motor spec question (product #1200)

Product 1200 is a six-lead stepper motor than can be used as unipolar or bipolar. The specs say 1.2 amps/3.3 ohms per phase, but in this case, it is not clear what the data sheet defines as a “phase”. Is the winding resistance 6.6 ohms if the center tap is ignored in bipolar mode, or is it 3.3 ohms?

While pondering this question I looked up what Dr. Jones of “Jones on Stepping Motors” homepage.cs.uiowa.edu/~jones/step/types.html has to say about current limits for such motors in bipolar configuration, and ran into these interesting comments:

The latter sentence suggests that in bipolar configuration, to get the most torque out of this motor under safe, long term operating conditions, the maximum steady state current per winding is 0.6 amps/phase. What do the Pololu engineers advise?

The resistance across the entire coil of that stepper motor is 6.6ohms. We tested one of those stepper motors and were able to get to much higher speeds under load and exert more torque when the current limit was set to 1.2A than when it was set to 0.6A, so it seems that the saturation discussed in the article is not happening here. In addition, we have been advising people for years to use this as a bipolar stepper motor with a current limit of 1.2 A, and we have not heard of it causing any problems.

-Claire